code: def test_missing_yarn():
      with pytest.raises(
          SystemExit, match="This machine is missing 'yarn'"
      ):
          cmd_react_ui_init._check_react_prerequisites()
  
file_path: pytorch-lightning/tests/tests_app/cli/test_cmd_react_ui_init.py
imports: import os
  import lightning.app
  import pytest
  from lightning.app.cli import cmd_init, cmd_react_ui_init
  from lightning.app.testing.helpers import _RunIf
label_desc: Use image node_id 3 for calling a global function with example usage: test_missing_yarn() without return types